Quiz 3

Describe the structure of the cnidarian nervous system

- 2 nerve nets; base of epidermis & gastrodermis - Bidirectional transmission at synapses - Medusae also have a nerve ring and marginal sense organs called rhopalia

Describe the distinguishing features of Class Anthozoa

- All marine - Exclusively polyps; no medusa stage - Solitary or colonial - Gastrovascular cavity is subdivided by septa - Three subclasses: Hexacorallia, Octocorallia, and Ceriantipatharia

Describe the distinguishing features of Class Scyphozoa

- All marine - Medusa is the prominent stage in the life cycle - Bell-like morphology - Free-swimming, solitary carnivores

Compare and contrast the structure and function of the asconoid, syconoid, and leuconoid canal systems (including being able to trace the flow of water through each system)

- Asconoid: Simplest form of sponges, with canals leading directly from the outside to the interior. 1. Ostium 2. Spongocoel 3. Osculum - Syconoid: A type of canal system in certain sponges. The choanocytes lie in canals 1. Dermal ostium 2. Incurrent canal 3. Prosopyle 4. Radial canal 5. Apopyle 6. Spongocoel 7. Osculum - Leuconoid: The choanocytes occupy distinct chambers. 1. Ostia 2.Incurrent Canal 3.Prosopyles 4.Flagellated Chambers (lined with choanocytes) 5.Apopyles 6.Excurrent Canals 7.Oscula

Describe the distinguishing features of Class Cubozoa

- Box/cube shape of their bell - Medusa is the predominant form - Small - Velarium: increasing swimming efficiency

Explain why sponges are important ecologically

- Important habitat - Help build and stabilize reef for community - Nutrient cycling

Describe how sponges acquire food

- In order to obtain food, sponges pass water through their bodies in a process known as filter-feeding. - There are carnivorous sponges that eat small crustaceans that get stuck in their spicules

Describe the structure of the digestive system and feeding strategies in Planaria

- Many Turbellarians are predators that feed on Protozoa, insect larvae, small crustaceans, mollusks and small annelid worms - Some feed on algae or harbor photosynthetic symbionts

Describe the distinguishing features of Class Hydrozoa

- Marine - Colonial in form - Life cycle includes both an asexual polyp & a sexual medusa stage

Describe the anatomy of a moon jelly: identify the gonads, gastric pouches and canals that make up the gastrovascular system

- Moon jelly can easily be distinguished by the 4 horseshoe shapes on its central disc. These structures are the gonads and are under the stomach. - The gastric pouches are radial divisions of the stomach that help to increase surface area. - The radial canals branch off of the ring canal. Both of these structures allow water to move through the jellyfish and can help with movement.

List and describe the function of the major cell types comprising the sponge body

- Pinacocytes: Flattened cells composing dermal epithelium in sponges. Covering and lining the sponge. - Myocytes: Contractile cell (pinacocyte) in sponges. Line the pores and oscula to shut down water flow. - Archaeocytes: Ameboid cells of varied function in sponges. Help with food breakdown and reproduction. Ability to differentiate into any more specialized cell types. - Sclerocytes: An amebocyte in sponges that secretes spicules. - Spongocytes: A cell in sponges that secretes spongin. - Collenocytes: A type of cell in sponges that is star-shaped and apparently contractile. - Choanocytes: One of the flagellated collar cells that line cavities and canals of sponges. Move water through sponge body

Describe the lifecycle of Scyphozoans and contrast it with the lifecycle of anthozoans

- Sperm + Zygote - Ciliated planula larva - Planula Settles - Scyphistoma - Early strobila - Strobila - Ephyra - Medusa

Describe the structure of a hydrozoan colony

- Typical colony has a base, a stalk and one or more terminal zooids - Perisarc: Protective, nearly transparent, non-living chitinous sheath that helps to support the colony - Zooids - Polymorphic: Gastrozooids (Hydranths) & Gonozooids (Gonangia)

Describe the life cycle and larval stages of Digenetic flukes

1. Adult 2. Egg 3. Miracidium 4. Sporocyst 5. Redia 6. Cercaria 7. Metacercaria

List the distinguishing features of Phylum Cnidaria

1. Cnidocytes present, typically housing stinging organelles called nematocysts 2. Entirely aquatic, some in freshwater, but most marine 3. Radial symmetry or biradial symmetry around a longitudinal axis with oral and aboral ends; no definite head 4. Two types of individuals: polyps and medusae 5. Adult body two-layered (diploblastic) with epidermis and gastrodermis derived from embryonic ectoderm and endoderm, respectively 6. Mesoglea, an extracellular matrix ("jelly"), lies between body layers; amount of mesoglea variable; mesoglea with cells and connective tissue from ectoderm in some 7. Incomplete gut called gastrovascular cavity; often branched or divided with septa 8. Extracellular digestion in gastrovascular cavity and intracellu- lar digestion in gastrodermal cells 9. Extensible tentacles usually encircle mouth or oral region 10. Muscular contractions via epitheliomuscular cells, which form an outer layer of longitudinal fibers at base of epidermis and an inner layer of circular fibers at base of gastrodermis; modifica- tions of plan in hydrozoan medusa (independent ectodermal muscle fibers) and other complex cnidarians 11. Sense organs include well-developed statocysts (organs of balance) and ocelli (photosensitive organs); complex eyes in members of Cubozoa 12. Nerve net with symmetrical and asymmetrical synapses; diffuse conduction; two nerve rings in hydrozoan medusae 13. Asexual reproduction by budding in polyps forms clones and colonies; some colonies exhibit polymorphism1 (different polyp types within a colony) 14. Sexual reproduction by gametes in all medusae and some polyps; monoecious or dioecious; holoblastic indeterminate cleavage; planula larval form 15. No excretory or respiratory system 16. No coelomic cavity

Describe the distinguishing features of Phylum Ctenophora

1. Eight rows of combs (ctenes) arranged radially around body 2. Colloblasts, adhesive cells used in prey capture, present in most 3. Entirely marine 4. Symmetry biradial; arrangement of internal canals and position of the paired tentacles change the radial symmetry into a combi- nation of radial and bilateral 5. Body ellipsoidal or spherical in shape with oral and aboral ends; no definite head 6. Adult body with gelatinous middle layer containing muscle cells; derivation of middle cellular layer controversial (ectodermal vs. endodermal) affecting status as diploblastic or triploblastic 7. Complete gut; mouth opens into pharynx; gut with a series of branching gastrovascular canals; gut terminates at anal pore; wastes exit via anal pore and mouth 8. Extracellular digestion in pharynx 9. Two extensible tentacles occur in most 10. Muscular contractions via muscle fibers (cells), not epithelio- muscular cells 11. Nervous system consisting of a subepidermal plexus concen- trated around the mouth and beneath the comb plate rows; an aboral sense organ (statocyst) 12. Reproduction monoecious in most; gonads (endodermal origin) on the walls of the digestive canals, which are under the rows of comb plates; mosaic or regulative cleavage within embryos; cydippid larva 13. No respiratory system 14. No coelomic cavity

Describe the general characteristics of Phylum Platyhelminthes

1. No clear defining feature 2. In marine, freshwater, and moist terrestrial habitats 3. Turbellarian flatworms are mostly free-living; classes Monogenea, Trematoda, and Cestoda entirely parasitic 4. Bilateral symmetry; definite polarity of anterior and posterior ends; body flattened dorsoventrally 5. Adult body three-layered (triploblastic) 6. Body acoelomate 7. Epidermismaybecellularorsyncytial (ciliatedinsome); rhabdites in epidermis of most Turbellaria; epidermis a syncytial tegument in Monogenea, Trematoda, Cestoda, and some Turbellaria 8. Gut incomplete, may be branched, absent in cestodes 9. Muscular system primarily of a sheath form and of mesodermal origin; layers of circular, longitudinal, and sometimes oblique fi- bers beneath the epidermis 10. Nervous system consisting of a pair of anterior ganglia with longitudinal nerve cords connected by transverse nerves and located in the mesenchyme in most forms 11. Sense organs include statocysts (organs of balance) and ocelli 12. Asexual reproduction by fragmentation and other methods as part of complex parasitic life cycles 13. Most forms monoecious; reproductive system complex, usually with well-developed gonads, ducts, and accessory organs; internal fertilization; development direct in free-swimming forms and those with single hosts; complicated life cycle often involv- ing several hosts in many internal parasites 14. Excretory system of two lateral canals with branches bearing flame cells (protonephridia); lacking in some forms 15. Respiratory, circulatory, and skeletal systems lacking; lymph channels with free cells in some trematodes

Define hydrostatic skeleton

A mass of fluid or plastic parenchyma enclosed within a muscular wall to provide the support necessary for antagonistic muscle action

Define zooxanthellae

A minute dinoflagellate alga living in the tissues of many types of marine invertebrates.

Define strobila

A stage in the development of the scyphozoan jellyfish. Also, the chain of proglottids of a tapeworm.

Define syncytial tegument

A unique multinucleate nonciliated epidermis occurring in many parasitic flatworms; also called a neodermis.

Define scolex

An attachment organ or holdfast of a tapeworm; bears suckers and, in some, hooks, and posterior to it new proglottids are differentiated.

Describe different patterns of asexual and sexual reproduction in sponges

Asexual Reproduction - Somatic embryogenesis: Complete reorganization of the structure & functions of participating cells or bits of tissue. - Fragmentation followed by regeneration: A sponge breaks into parts that are each capable of becoming a new sponge. - External bud formation: After reaching a certain size, may become detached from the parent and float away to form new sponges, or they may remain to form colonies - Internal buds (gemmules): Formed in freshwater sponges and some marine sponges. Sexual Reproduction -Spawning: Most sponges are monoecious (male & female sex cells) and gametes are derived from choanocytes or from archaeocytes.

Describe asexual and sexual reproduction

Asexual reproduction -Often occurs by fragmentation -Worm constricts behind pharynx, and divides into two parts which each regenerate missing pieces to form a new worm Sexual reproduction -Monoecious with cross fertilization -Some groups perform hypodermic impregnation (aka: Penis Fencing) -Sperm is deposited in parenchyma and migrates to ovaries

Describe the lifecycle of a hydrozoan colony and compare and contrast it with the Scyphozoan and Anthozoan life cycles

Asexual: Budding -Generates new feeding polyps (hydranths) or medusa buds (produced in gonangia) -Increases the size of the colony Sexual -Young medusae leave colony as free swimming individuals -Produce gametes that develop into planula larvae -Settles out and starts a new colony

Define hypodermic impregnation

Basically stab each other to inject sperm. "Penis fencing"

Explain what coral bleaching is and why it is problematic.

Bleaching happens when sea temperatures get too high or low, causing the algae to get 'stressed out' and leave the coral. Coral reefs are home to 25% of the world's marine species. Coral can be used in some types of medicine and the beautiful reefs provides income for locals from tourists who pay to visit them. Coral bleaching is destroying the homes of several species and a useful resource to us.

Define gastrovascular cavity

Body cavity in certain lower invertebrates that functions in both digestion and circulation and has a single opening serving as both mouth and anus.

Define proglottids

Boxlike portion of a tapeworm containing a set of reproductive organs; usually corresponds to a segment.

Explain what a syncytial tegument is and why it is beneficial for parasitic forms

Cells that are interconnected. Outer covering where cells are all fused together. It gives parasites greater resistance to host immune system.

Define epitheliomuscular cells

Cells with contractile fibers at their bases

Define siphonoglyph

Ciliated furrow in the gullet of sea anemones.

Describe the organization of the Cnidarian body and compare and contrast between polyp and medusa stages

Cnidarian body: Saclike body plan, central gastrovascular cavity, body wall consisting of an outer epidermis, inner gastrodermis, with mesoglea in between Polyp: Tentacles, mouth, epidermis, mesoglea and gastrovascular cavity. Tubular shape & sessile. Medusa: Same as polyp but bell shape body and mobile.

Compare and Contrast Phylum Ctenophora and Phylum Cnidaria

Cnidarians live in both freshwater and marine habitats while ctenophores only live in the sea. Cnidarians are diversified animals than ctenophores. Both cnidarians and ctenophores are diploblastic animals. Cnidarians exhibit radial symmetry whereas ctenophores exhibit biradial symmetry. Both contain tentacles, surrounding their mouth. The main difference between cnidarians and ctenophores is their body symmetry.

Define colonial

Composed of interconnected individuals called zooids

Describe locomotion within this phylum

Ctenophores move through the water by beating their comb rows but they also have a complex array of definitive muscle cells.

Define nerve net

Diffuse network of nerves. 1 at the base of the epidermis & gastrodermis

Distinguish between endoparasites and ectoparasites

Ectoparasites are those that live on the surface of the host. Endoparasites are those that live inside the host.

Briefly describe the lifecycle of a tapeworm

Eggs, larvae, and adults. Adults inhabit the intestines of definitive hosts, mammalian carnivores. Several of the adult tapeworms that infect humans are named after their main intermediate host.

Define cellular, ciliated epidermis

Epidermis is made up of distinct cells

Define oscula (osculum)

Excurrent opening in a sponge.

Define dimorphism

Existence within a species of two distinct forms according to color, sex, size, organ structure, or behavior. Occurrence of two kinds of zooids in a colonial organism.

Explain why the pork tapeworm is more problematic than the beef tapeworm for humans

Fertilized eggs digested by human instead of pig and the larval stages can migrate and insist in human tissues. They like to go up to the brain and insist.

Give examples of organisms found within this class

Freshwater jelly, freshwater polyps (Hydra), Obelia, Portuguese man o' war, chondrophores, "air fern", and pink-hearted hydroids

Contrast the body forms of Hexactinellida and Demospongiae

Hexactinellida - Spicules w/ 6 rays -Syncytial trabecular reticulum - Radially symmetrical, vase- or funnel-shaped bodies usually attached by stalks of root spicules to a substratum Demospongiae - Spicules NOT w/ 6 rays - Spongin network often present - Varied in color and shape - Red boring, encrusting, finger, variable and tube sponge

List the 4 classes of extant sponges and describe the key features that characterize each class

Homoscleromorpha: Marine sponges - Encrusting or cushion-shaped - Often found in caves and other dark ecosystems - Spicules (if present) are siliceous - Appear to have a basement membrane underlying the pinacoderm - Formerly considered to be part of Class Demospongiae, but recent molecular evidence has shown that it is a separate class Calcarea: - Spicules are composed of calcium carbonate - Tend to be small - Have asconoid, syconoid, and leuconoid canal systems Demospongiae: - Spicules may be bound together by spongin - 95% of living sponge species - All members of the class are leuconoid - Varied in color and shape Hexactinellida: - 6-rayed siliceous spicules - Trabecular reticulum: composed of a single, continuous syncytial tissue

Define ostia (ostium)

Incurrent pores in a sponge.

Define septa

Inward extensions of the body wall.

Define cnidocyte

Modified interstitial cell that holds the nematocyst; during development of the nematocyst, the cnidocyte is a cnidoblast.

Define spongin

One form of collagen. Fibrous, collagenous material forming the skeletal network of demosponges.

Define rhopalium

One of the marginal, club-shaped sense organs of certain jellies; tentaculocyst.

Define duo gland system

Organs in the epidermis of most turbellarians, with three cell types: viscid, releasing gland cells and anchor cells.

Describe the anatomy of a sponge

Outer Layer: The Pinacoderm - The pinacoderm is similar to an epithelial tissue, but whether or not it should be considered a true tissue is debated by scientists. Middle Layer: The Mesohyl - Gelatinous extra cellular matrix that forms the "connective tissue" of sponges - Contains spicules, various fibrils, and several cell types Inner Layer: The Choanoderm

Define opisthaptor

Posterior attachment organ of a monogenetic trematode.

Define ephyra

Refers to castlelike appearance. Medusa bud from a scyphozoan polyp.

Describe the rhopalia and the function of eyes

Rhopalia are present, each housing six eyes in addition to other sense organs. There are two copies of each of three kinds of eyes: two forms of ocelli, and a sophisticated camera-type eye with a cornea and cellular lens.

Define rhabdites

Rodlike structures in the cells of the epidermis or underlying parenchyma in certain turbellarians. They are discharged in mucous secretions.

Define statocyst

Sense organ of equilibrium; a fluid-filled cellular cyst containing one or more granules (statoliths) used to sense direction of gravity.

Explain why cephalization/ bilateral symmetry is advantageous for organisms moving in an oriented direction

Sensory structures are being concentrated in that head ends up becoming more well developed.

Describe the advantages of having both sexual and asexually reproducing phases in the lifecycle

Sexual reproduction is going to increase genetic diversity and asexual reproduction is going to increase numbers dramatically.

Describe the life cycle of an Anthozoan

Sexual: -Fertilized egg -Embryo -Planula larva -Symbionts Asexual -Anemone w/ pedal lacerates -Pedal lacerate -Young Anemone

Define flame cells

Specialized hollow excretory or osmoregulatory structure of one or several small cells containing a tuft of flagella (the "flame") and situated at the end of a minute tubule; connected tubules ultimately open to the outside

Explain why sponges are important pharmacologically

Sponges are among the richest sources of pharmacologically-active chemicals from marine organisms

Define nematocyst

Stinging organelle of cnidarians.

Define cnida

Stingingor adhesive organelles formed within cnidocytes in phylum Cnidaria; nematocysts are a common type.

Distinguish between subclass Hexacorallia and subclass Octocorallia.

Subclass Hexacorallia: Sea Anemone -Sea anemones, stony corals that are reef forming - All polyps, generally with 6-fold symmetry. Subclass Octocorallia: Soft Corals & Gorgonians - All are colonial & gastrovascular cavities communicate via solenia (gastrodermal tubes) - Octomerous symmetry - Eight pinnate tentacles - Endoskeletal support system composed of limy spicules or horny protein - Great variation in colony form

Describe the anatomy of a reef building coral

Tentacles, mouth, pharynx, septum, gastrovascular cavity, septal filament, sclerosepta, calcium carbonate skeleton

Explain what cephalization is and why cephalization is correlated with bilateral symmetry

The evolutionary development of the head and concentrations of sense organs at head or anterior end. It is correlated because there's just one cut through center of organism that will provide mirror-image halves.

Define mesoglea

The layer of jellylike or cement material between the epidermis and gastrodermis in cnidarians and ctenophores.

Explain what is unique about the life history of the immortal jellyfish

The medusa can revert to polyp stage when stressed out. This can be done repeatedly.

Define scyphyistoma

The polyp form of a scyphozoan.

Define polymorphism

The presence in a species of more than one structural type of individual; genetic variation in a population.

Define spicules

The skeletal framework of a sponge can be fibrous and/or rigid. When present, the rigid skeleton consists of calcareous or siliceous support structures.

Describe how parasites can manipulate the behavior of their hosts to increase their chances of completing their life cycles

They get ants to climb up the tips of blades of grass and bite down on them to stay there. They will then get eaten by cattle. Parasites will also go up to snail's tentacles and mimic a maggot to get eaten.

Describe how the anatomy of parasitic flatworms is adaptive for a parasitic life cycle

They have parts that make it harder for the host to get rid of them. Suckers allow them to stay attached. Syncytial tegument prevents the host immune system from attacking.

Define acontia threads

Threadlike structure bearing nematocysts located on mesentery of sea anemone.

List the classes of Platyhelminthes found within clade Neodermata

Trematoda, Monogenea and Cestoda

Describe how humans can be infected by tapeworms and how infections can be prevented or treated

Under/Uncooked meat. This can be prevented by cooking meat and treated via medicine.

Define protonephridia

flame cells, excretory systems found in platyhelminthes / flatworms

Define pedal disc

surface opposite to the mouth, and generally serves to attach the anemone to the substrate, or hard surface, upon which it lives.

List the distinguishing characteristics of Phylum Porifera

•All aquatic; mostly marine •Body Symmetry: None or Radial body symmetry •Body organization: Cell/Tissue* level - Multicellular body composed of an aggregation of differentiated cell types with various functions - Body with pores and canals - No organs or organ systems, but can still respond to stimuli. - Presence of true tissues is a subject of debate. •Adults are sessile and attached to the substrate

Describe the anatomy of a tapeworm

•Endoparasites (primarily of vertebrates) •Very specialized for parasitic existence -Syncytial tegument -No mouth or digestive system -Specialized scolex for attachment •Excretory and nervous systems are somewhat similar to other flatworms •Long, flat bodies composed of a scolex and strobila (series of proglottids) -Formed by budding -Mature proglottids each contain a set of male and female reproductive organs -Mature proglottids can produce tens of thousands of fertilized eggs

Describe the anatomy of Class Turbellaria

•Most turbellarians have a cellular, ciliated epidermis -Some have a syncytial epidermis •Several glands: -Mucus glands •Secrete mucus which is important for locomotion -Duo gland system allows the animal to attach and detach to substrates •Rod shaped rhabdites can generate a protective mucus sheath •Body wall contains several layers of muscles: circular, longitudinal, dorsoventral

Describe the structure and function of the protonephridial system and flame cells in flatworms.

•Nitrogen is eliminated primarily as ammonia across the body surface •Excess water is eliminated using protonephridia with flame cells